To format the link:

Click post reply!, Then in the reply box click the Globe icon with the chain link on it. It'll bring up some boxes. In the first put your username in the second paste your link. That's it.

On your song I guess it would depend on where you are hosting your take. If it's soundclick you can find different ways to link your page and song in the band administration section. I heartily recommend linking to your page rather than the song. Sean gets all pissy because the direct links don't work for him. :p